JPH0383617A - Production of hot runner manifold block - Google Patents

Abstract

PURPOSE:To simplify the production of a manifold block by a method wherein the manifold block is divided into the nozzle side block and the gate side block of a molder and some parts of hot runner channels including the diverging point of the hot runner channels are produced on both the parting faces of both the blocks and finally both the blocks are welded together by diffusion welding. CONSTITUTION:A manifold block 30 is divided into the nozzle side block 30A and the gate side block 30B of a molder. Next, some parts of hot runner channels 32 including the diverging point 32a of the hot runner channels 32 are produced on the parting faces 34 of both the blocks 30A and 30B. Thus, the hot runner channels 32, which allow to prevent resin from stagnating, can easily be produced and the lengths of the hot runner channels arriving respective cavities can be adjusted on the parting faces 34.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a hot runner manifold block in which a hot runner path branching from a molding machine nozzle side to a gate side is formed. It is.

(Conventional technology) Hot runner injection molds are suitable for fully automatic molding because there is less wastage of molding material, and the gate part is automatically separated and there is no need to take out the launch part. . When performing multi-cavity molding with such a hot runner mold, it is recommended to use a hot runner manifold block with a hot runner path that branches from the molding machine nozzle side to the gate side. It will be done.

Conventionally, in the hot runner manifold block described above, a hot runner path has been formed inside by drilling, as shown in FIGS. 3 and 4. That is,
A main path 2 having an opening end 2a on the molding machine nozzle side, a plurality of terminal paths 4 having an opening end 4a on the gate side, and a branch path 8 that communicates the main path 2 with each terminal path 4 are formed by drilling. The hot runner path 12 was formed by closing the end of the branch path 8 with a stopper 10 .

By the way, in order to obtain a homogeneous molded product from each cavity in a multi-cavity injection mold, it is important to set the hot runner path length in the hot runner manifold block equally for each cavity. It is.

However, in the above-described conventional method for manufacturing a hot runner manifold block, the hot runner path is formed by drilling, so the shape of the hot runner path is limited to a combination of straight lines. As shown in the figure, in a six-cavity hot runner manifold block 6 in which gate-side opening ends 4a are arranged in two stages and three rows, hot runners extend from the molding machine nozzle-side opening end 2a to each gate-side opening end 4a. It was not possible to equalize the path lengths.

As an attempt to equalize the hot runner path lengths, it is conceivable to employ processing methods as shown in FIGS. 5 and 6 and further in FIG. 7.

The hot runner manifold block 14 shown in FIGS. 5 and 6 has gate-side open ends Lea arranged in 4 stages and 8 rows 32.
The hot runner path is shown to equalize the length of the hot runner path from the nozzle-side opening end 18a of the molding machine to each gate-side opening end 16a when forming two molding machines. However, as shown in these figures, it is extremely difficult to bury and fix the stopper 22 in the middle of the drilled path 20, and such a manifold block cannot actually be obtained.

In contrast, the hot runner manifold block 24 is divided into a molding machine nozzle side block 24A and a gate side block 24B as shown in FIG.
By forming the hot runner by drilling, it is possible to set the hot runner path length uniformly for each cavity, and this manufacturing method has been employed in the past.

(Problem to be Solved by the Invention) However, in the hot runner manifold block 24 shown in FIG.
Since A and the gate side block 24B are stacked, the thickness of the manifold block 24 doubles, which causes problems in mold deformation due to thermal expansion and mold rigidity.

In addition, when forming a hot runner path by drilling, it is necessary to make the corners of the hot runner path a little extra long. The resin that remains in the manifold tends to undergo thermal deterioration, which may cause burns to be mixed into the molded product. In this case, in order to prevent resin from accumulating, some measures have been taken to embed stop plugs in the corners of the hot runner path so that the corners are shaped to prevent resin from accumulating. This method is technically difficult, lacks reliability because it cannot be confirmed after embedding, and has the drawback of high processing costs.

Furthermore, as shown in FIG. 7, the manifold block 2B
If you decide to manufacture it by dividing it, both blocks 2
It is necessary to integrate blocks 4A and 24B, but the method for this integration is to finish the flatness and surface roughness of the mating surfaces of both blocks 24A and 24B with high precision and fasten them with bolts, or to connect both blocks 24A and 24B with bolts. , 24B, a method is adopted in which the mating surfaces of 24B are infiltrated with weld metal and brazed. However, the former method requires a special finishing machine to improve the finishing accuracy of the split surface to a level that prevents resin from leaking, and the larger the manifold block, the more difficult and costly it is to process. There is a risk that the resin may deform due to distortion due to heat or stress, and the resin may leak. On the other hand, the latter method of infiltrating molten metal is
It is difficult and unreliable to treat the surface so that molten metal can penetrate easily, and furthermore, it is impossible to confirm whether the metal has penetrated the entire surface after it has penetrated.
Occasionally, there is a risk of sudden cracking from the splitting surface during molding, and the processing cost is also high.

The present invention has been made in view of the above circumstances, and provides a manifold block for a hot runner that can obtain a homogeneous and high-quality molded product from each cavity at a low cost and with an increased wall thickness. The purpose of this invention is to provide a method that can be manufactured without any problems.

(Means for Solving the Problems) The method for manufacturing a manifold block for a hot runner according to the present invention is such that, like the manifold block in a cold runner type injection mold (see Fig. 8), a runner is formed on the block dividing surface. By forming part of the path to include the branch point, the launch path length for each cavity can be equalized without thickening the manifold block, and both blocks can be welded together by diffusion welding. By doing so, the inconvenience associated with the divided formation of the manifold block is eliminated, thereby achieving the above object. That is, a method for manufacturing a hot runner manifold block in which a hot runner path branching from a molding machine nozzle side toward a gate side is formed, the manifold block being divided into a molding machine nozzle side block and a gate side block. and forming a part of the hot runner path on the dividing plane of both blocks so that a branch point of the hot runner path is included,
The invention is characterized in that both blocks are then welded together by a diffusion welding method.

(Function) As shown in the above configuration, the manifold block is divided into a molding machine nozzle side block and a gate side block, and a part of the hot runner path is placed on the dividing surface of these two blocks at a branch point of the hot runner path. Since the hot runner path is formed so as to be included, it is possible to easily form a hot runner path that can prevent resin from stagnation, and the length of the hot runner path for each cavity can be adjusted at the dividing plane. This makes it possible to equalize the hot runner path length without increasing the thickness of the manifold block and at low processing costs.

In addition, after the predetermined hot runner path is formed, both of the above blocks can be welded by diffusion welding (i.e., applying pressure and heating to the materials to be welded in a vacuum or in a protective atmosphere to cause diffusion between the base materials). Since the two blocks are welded together using a welding method, the two blocks can be reliably integrated, thereby preventing resin leakage between the two blocks.

(Effects of the Invention) Therefore, according to the present invention, it is possible to manufacture a hot runner manifold block that can obtain a homogeneous and high-quality molded product from each cavity at low cost and without increasing the wall thickness. can.

(Examples) Examples of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing a hot runner manifold block 30 manufactured by an embodiment of the hot runner manifold block manufacturing method according to the present invention.
FIG. 2 is a view taken along the line ■-■.

This hot runner manifold block 30 has two stages 3
This is a manifold block for a six-cavity hot runner type injection molding mold arranged in a row, and is made by integrating two blocks divided into a molding machine nozzle side block BOA and a gate side block 30B. ing. The molding machine nozzle side block 30A is formed with a main path 32A that extends vertically from the molding machine nozzle side opening end 32Aa to the dividing surface 34 of both blocks, and the gate side block 30B is formed with six gates. Six terminal paths 32B extending vertically from the side opening end 32Ba to the dividing surface 34
are formed, and furthermore, both blocks 30A and 30
The main path 32A is provided on the end surface of B on the dividing surface 34 side.
One side portion of six radial paths 32C that communicate with the end paths 32B is formed, so that the hot runner path 32, which branches into six from the molding machine nozzle side toward the gate side, is connected to the manifold block. 30.

Among the six radial paths 32C, the four radial paths 32C that communicate with the four terminal paths 32B located on both the left and right sides of the upper and lower stages are slightly bent and have the same shape. The two radial paths 32C communicating with the two terminal paths 32B located at the center of each stage are formed in the same shape with a large bend so as to have the same path length as the four radial paths 32C. .

The manifold block 30 is manufactured as follows.

First, the manifold block 30 is divided into the molding machine nozzle side block 30A and the nozzle side block 30B, and the molding machine nozzle side block 30Al: has one side of the main path 32A and the radial path 32C
The remaining one side portion of the terminal path 32B and the radial path 32C is formed in the nozzle side block 30B by cutting using a drilling machine, a milling machine, or the like. In this way, both blocks 80A.

The hot runner path 32 is attached to the dividing surface 34 of 30B.
A part of the branch point 82a of the hot runner path 32
By forming the molding machine nozzle side opening end 32A a to each gate side opening end 32B.
The hot runner path length up to a is defined as the radial path 32
Equalization can be easily achieved by setting the shape of C.

Next, the hot runner path forming surfaces of each of the blocks 30A and 30B are polished to smooth the hot runner path. At this time, the hot runner path forming surface may be further plated and polished again.

Thereafter, each of the blocks 30A and 30B is positioned so as not to be misaligned on one side of the radial path 32C of the hot runner path 32, and
After joining in step 4, both blocks 30A and 30B are welded and integrated by diffusion welding.

When the above-mentioned diffusion welding method is adopted, the finishing accuracy of each block BOA and 30B at the dividing surface 34 is approximately 0.02 mm or less in terms of flatness to ensure that the entire surface is fixed and that resin leaks during molding. There is almost no risk of cracking or cracking. This value is about 10 times rougher than the processing accuracy when preventing resin leakage only with the surface accuracy of the dividing surface 34 without using the diffusion welding method, and can be adequately handled by normal processing. It is at a possible level.

The material of both blocks 30A and 30B is 5US
(stainless steel) and the like are preferred (particularly preferred when the hot runner path forming surface is not plated).

Next, the performance of the hot runner manifold block manufactured according to this example will be explained using experimental data.

A comparison is made between the manifold block 30 according to the present embodiment shown in Figs. 1 and 2 and the conventional manifold block 6 shown in Figs. 3 and 4, using a six-piece injection mold for each. I went there.

■ Experimental conditions 1) Molded product weight: 2g/piece il) Material resin: Polyethylene (weight change is large due to molding pressure change) 111〉 Molding temperature: 180°C M Manifold block material: 5TAVAX (SUS
system; product name) ■) Regarding the conventional manifold block 6, a stopper is processed and embedded in the corner of the hot runner path 12 to prevent resin from accumulating in the corner, and the hot runner path t2 is
A fluid abrasive was filled inside and the polishing was performed by moving it back and forth.

■ Experimental comparison items i) Difference in molded product weight between cavities ii> Probability of burnt contamination in the molded product 1ii) Number of shots required to change the color of the molded product when changing the color of the resin material ■ Experimental results・The opening of the cavity due to the weight of the molded product is thought to be caused by an imbalance in the hot runner path length.

・The number of burns and color change shots was determined by cutting each manifold block into 1 section at the block dividing plane after the experiment and checking the condition of the resin in the hot runner path. Burnt resin remained on the inside of the joint and the corner of the hot runner path. No burnt resin was found in the hot runner path in the manifold block of this example. In addition, the diffusion welded surface had no unwelded parts and was completely welded and integrated.

As is clear from the above experimental results, according to this example, the difference in molded product weight between cavities is extremely small compared to the conventional example, and a homogeneous molded product can be obtained from each cavity. In addition, the probability of scorch entering the molded product is significantly reduced, making it possible to obtain a high-quality molded product.

Furthermore, since the number of color change shots is significantly reduced, molding costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view (cross-sectional view taken along the line I-1 in FIG. 2) showing a hot runner manifold block manufactured by the hot runner manifold block manufacturing method according to the present invention. 1 is a view taken along the line ■-■ in FIG. 1, FIG. 3 is a view similar to FIG. IV-TV line sectional view, 5th and 6th
The figures are a plan sectional view and a side sectional view showing another conventional example, FIG. 7 is a perspective view showing still another conventional example, and FIG. 8 is a
FIG. 2 is a vertical cross-sectional view showing a general cold runner manifold block. 30...Hot runner manifold block 30A.
...Molding machine nozzle side block 80B...Gate side block 32...Hot runner path 34...Dividing surface 32a...Branch point Fig.■ 3 Fig. 7

Claims (1)

[Claims] A method of manufacturing a hot runner manifold block in which a hot runner path branching from a molding machine nozzle side toward a gate side is formed, the manifold block being divided into a molding machine nozzle side block and a gate side block. The hot runner is characterized in that a part of the hot runner path is formed on the dividing surface of both blocks so that a branching point of the hot runner path is included, and then both blocks are welded by diffusion welding. How to make a manifold block for a runner.